A driver and a driving method of a display device that includes a signal controller that processes image data input from an external circuit and a memory that is connected to the signal controller, wherein the signal controller includes a data converter that converts the image data and outputs the converted image data to the memory, and the data converter includes a data output unit that converts and outputs the image data and a data input unit that restores the image data input from the memory. Accordingly, the number of data transitions between the signal controller and the memory can be minimized to reduce current consumption and to reduce EMI.